Abstract
BackgroundAwareness of the cumulative stress placed on first responders and tactical operators is required to manage acute fatigue, which can impair occupational performance, and may precipitate negative chronic health outcomes. The aim of this review was to investigate the utility of heart rate variability (HRV) to monitor stress and allostatic load among these populations.MethodsA systematic search of Academic Search Complete, MEDLINE complete, PsycINFO, SPORTDiscus and Scopus databases was conducted. Eligibility criteria: original peer reviewed research articles, written in English, published between 1985 and 2020, using human participants employed as a first responder or tactical operator, free from any psychological disorder.ResultsOf the 360 articles screened, 60 met the inclusion criteria and were included for full text assessment. Articles were classified based on single or repeated stressor exposure and the time of HRV assessment (baseline, during stressor, post stressor). Singular stressful events elicited a reduction in HRV from baseline to during the event. Stressors of greater magnitude reduced HRV for extended durations post stressor. Lower resting HRV was associated with lower situational awareness and impaired decision-making performance in marksmanship and navigation tasks. There were insufficient studies to evaluate the utility of HRV to assess allostatic load in repeated stressor contexts.ConclusionA reduction in HRV occurred in response to acute physical and cognitive occupational stressors. A slower rate of recovery of HRV after the completion of acute occupational stressors appears to occur in response to stressors of greater magnitude. The association between lower HRV and lower decision-making performance poses as a useful tool but further investigations on within subject changes between these factors and their relationship is required. More research is required to investigate the suitability of HRV as a measure of allostatic load in repeated stress exposures for fatigue management in first responder and tactical operators.
Highlights
Awareness of the cumulative stress placed on first responders and tactical operators is required to manage acute fatigue, which can impair occupational performance, and may precipitate negative chronic health outcomes
Titles and abstracts were searched for combinations of the following terms with an ‘*’ indicating a truncation: ambulance personnel, armed forces, army, defence force*, emt, firefighters, fire fighters, fire-fighters, first respond*, air force, navy, paramedic*, police*, law enforcement, military, soldiers, troops, rescue worker*, rescue-worker*, coast guard, coast-guard, emergency, and heart rate variability, hrv, ans, autonomic, pns, parasympathetic, sns, sympathetic, vagal, and fatigue*, load*, stress, overtrain*, overreach*, recovery
Databases were searched from 1985 until 3rd August 2020 and were required to meet the following inclusion criteria: 1) the study recruited human participants that were currently employed as a first responder, tactical operator or completing the task(s) of these occupations; 2) the study reported on heart rate variability at ≥1 timepoint; 3) the study included a stressor that was applied to participants; 4) participants included in the study had no presence of psychological disorders; 5) the study was peer-reviewed and written in the English language
Summary
Awareness of the cumulative stress placed on first responders and tactical operators is required to manage acute fatigue, which can impair occupational performance, and may precipitate negative chronic health outcomes. Workers in physically and cognitively demanding occupations include emergency first responders (firefighters, paramedics), and tactical operators (law enforcement, military). These personnel are often required to complete physiologically demanding tasks that may be performed repeatedly over a long duration [1, 2]. Methods for assessing the effects of allostatic load, the cost of chronic exposure to physical and psychological stressors, is required to better optimise health and performance in these populations [9]
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